# CVE-2026-90169: ksmbd: free preauth sessions on connection teardown

CVE-2026-90169 is fixed in 2 products on 1 platform, first by DEBIAN-CVE-2026-90169, released September 23, 2026. It is not reported as exploited. Patch Radar priority: High.

- Web page: https://patchblox.com/security/cve/CVE-2026-90169
- Priority: High
- CVSS: 7.8 (Important)
- EPSS: 0.0025
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 17, 2026
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2026-90169

## Description

In the Linux kernel, the following vulnerability has been resolved:  ksmbd: free preauth sessions on connection teardown  SMB3.1.1 multichannel binding preserves the preauthentication hash in a preauth_session between the NTLM negotiate and authenticate requests. The binding NTLM negotiate allocates this object and returns STATUS_MORE_PROCESSING_REQUIRED. If the client disconnects before it sends the authenticate request, neither the authenticate nor error cleanup paths free the object.  Release any remaining preauthentication sessions when tearing down the connection. Initialize the list when allocating the connection so that this cleanup is safe regardless of the negotiated dialect.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.12.111-1 | [DEBIAN-CVE-2026-90169](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90169.md) | Sep 23, 2026 |
| Linux | linux Debian 14 | 7.2.6-1 | [DEBIAN-CVE-2026-90169](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90169.md) | Sep 23, 2026 |
| Linux | linux-6.12 Debian 12.15 (bookworm) | 6.12.111-1~deb12u1 | [DEBIAN-CVE-2026-90169](https://patchblox.com/security/data/fix/linux/debian-cve-2026-90169.md) | Sep 23, 2026 |

---

Data as of 2026-11-08T06:59:42Z UTC. Source: Patchblox Patch Radar (https://patchblox.com/security/patch-radar). Patchblox finds out-of-date software on Windows, macOS and Linux and updates it through release rings: https://patchblox.com/demo

Free to use with attribution: show "Data: Patchblox Patch Radar" with a link to https://patchblox.com/security/patch-radar. Terms, including what needs a written agreement: https://patchblox.com/security/patch-radar/use-the-data

Product names, logos and trademarks shown on Patch Radar belong to their respective owners. They are used only to identify the software each security fix applies to and to help readers find their platform. Their use does not imply any affiliation with, or endorsement by, those owners, and Patchblox is not affiliated with any of them.